| The information provided below is meant to educate | | | | Ceramic-on-Polyethylene |
| the patient about the options available to hip | | | | Your next option is a ceramic ball and polyethylene |
| replacement candidates. Your orthopedic surgeon | | | | liner. Ceramic heads are harder than metal and are |
| should explain to you which hip replacement is best | | | | the most scratch resistant implant material. The hard, |
| for you and why. | | | | scratch resistant, ultra-smooth surface can greatly |
| In a total hip replacement, both the thigh bone | | | | reduce the wear rate on the polyethylene bearing. |
| (femur) and the socket are replaced with implant | | | | The wear rate for this type of implant is less than |
| materials and prostheses. Specifically, a metal stem is | | | | Metal-on-Polyethylene. |
| inserted into your thighbone. Attached to the neck of | | | | One disadvantage found in Ceramic-on-Polyethylene |
| the stem is a hip ball, just over an inch in diameter. | | | | are the incidents of fractures, but newer, stronger |
| The hip ball fits into a liner. Together, the ball and liner | | | | ceramics have resulted in fewer of these. Overall, the |
| create the new joint. The liner is inserted into a metal | | | | wear rate for Ceramic-on-Polyethylene is 50% less |
| shell that in turn is anchored to your pelvis. But there | | | | than that of Metal-on-Polyethylene. |
| are a number of different approaches a surgeon can | | | | In terms of cost, Ceramic-on-Polyethylene is more |
| take, depending on her analysis of your particular | | | | expensive than Metal-on-Polyethylene, but less than |
| case. | | | | Ceramic-on-Ceramic. |
| Because of the advances in the last thirty years, | | | | Metal Ball and Metal Liner |
| several different types of implant materials have also | | | | Metal-on-Metal bearings were approved by the FDA |
| been found useful in hip replacement procedures. | | | | in 1999, offering the potential for greatly reduced |
| Each material has its own advantages and | | | | wear, with less inflammation and less bone loss. |
| disadvantages, but it is ultimately up to your surgeon | | | | One clear advantage of metal-on-metal implants is |
| which materials to use. Beyond the different types of | | | | the variety of femoral head sizes and neck lengths |
| materials, a surgeon must also decide whether to | | | | available (modularity). Metal-on-metal components |
| anchor the hip implant to the bone using cement | | | | allow the largest heads throughout the entire range |
| fixation or something called "bone ingrowth." | | | | of implant sizes. Large ball heads provide increased |
| Fixation | | | | range of motion and greater stability, which can |
| For bone ingrowth, the surface of the prostheses | | | | significantly reduce the risk of hip dislocation, a crucial |
| simulates the bone with a special granular surface into | | | | factor in the long-term success of an implant. |
| which the bone grows, thereby locking the implant | | | | Although wear is reduced, the wear products |
| into place. Cement fixation holds the implant in the | | | | (sub-microscopic particulates, soluble metal ions) are |
| bone by acting as a filler between the bone and the | | | | distributed throughout the body. This has raised |
| implant. It is made of a substance that is mixed at | | | | concerns about long-term bio-compatibility. At present |
| the operation and hardens into a durable, long lasting | | | | these are only concerns, for there have been no |
| polymer. | | | | definitive clinical findings that these wear products are |
| Modularity | | | | harmful. |
| You may also want to consult with your doctor | | | | Anatomic Size Metal-on-Metal Ball Heads |
| about the design of the implant. Modular systems | | | | Because the human femoral (ball) head is naturally |
| offer the ability to interface different sizes of | | | | large, it makes sense to implant a large, anatomic |
| femoral heads to fit over the stem; angles, sizes, and | | | | replacement. This was not possible in the past |
| lengths of the implant are made to fit your anatomy. | | | | because traditional polyethylene liners made smaller |
| The advantage of a modular system is that it gives | | | | femoral heads necessary. However, with the |
| the patient more flexibility. | | | | introduction of metal-on-metal implant components, |
| Choosing Hip Replacement Implant Material | | | | liners may be eliminated, allowing surgeons to use |
| The main issue that doctors and patients confront | | | | large femoral heads. Use of a larger ball head has |
| when choosing implant material revolves around the | | | | been shown to increase the range of motion an |
| wear debris that is released into your body from any | | | | individual may experience as well as decrease the |
| of the implant materials. Even the materials with the | | | | possibility of dislocation. |
| most wear debris (metal ball and polyethylene liners) | | | | Ceramic Ball and Ceramic Liner |
| show up only after many years (10-15). Nevertheless, | | | | Ceramic is the hardest implant material used in the |
| it is important to educate yourself about the various | | | | body, and has the lowest wear rate of all, to almost |
| options for hip replacement surgery. | | | | immeasurable amounts (1000 times less than |
| Metal-on-Polyethylene | | | | Metal-on-polyethylene). These implants have been |
| Because of its durability and performance, | | | | used in Europe for more than 30 years, and since |
| Metal-on-Polyethylene has been the leading artificial | | | | 2003 in the United States. |
| hip component material chosen by surgeons since | | | | Consequently, there is usually no inflammation or |
| FDA approval 30 years ago. The metal ball is cobalt | | | | bone loss, nor systemic distribution of wear products |
| chrome molybdenum alloy and the liner is | | | | in the body. New ceramics offer improved strength |
| polyethylene. | | | | and more versatile sizing options. However, there has |
| Metal-on-Polyethylene is the most understood and | | | | been a very few incidents reported of noises from |
| practiced of all the procedures. Using these materials, | | | | such implants. |
| a surgeon has a range of options to obtain stability in | | | | Hip-Resurfacing Option |
| the body while the operation is underway. This ability | | | | For younger patients, a total hip replacement may |
| to adapt and customize during the surgical procedure | | | | not be the best solution for their hip pain because it |
| is an important attribute of polyethylene. It is also the | | | | can mean difficult and numerous revisions later in life. |
| least expensive bearing. | | | | Hip resurfacing, however, leaves more of the bone in |
| The disadvantage of Metal-on-Polyethylene is | | | | place, giving these patients more time before a total |
| shedding over time. After 10 to 15 years, patients | | | | hip replacement becomes necessary. |
| who are extremely active may shed debris that | | | | Conclusion |
| results in joint inflammation and bone loss. However, | | | | If you are a candidate for hip replacement surgery, |
| new wear resistant polyethylene liners have been | | | | fixation, modularity, and implant materials are all topics |
| introduced, called "highly crosslinked polyethylene." If | | | | that factor into making the right decision. Your doctor |
| you are a very active individual or a relatively young | | | | should explain to you which procedure and materials |
| patient, your surgeon may prescribe an all-ceramic hip | | | | are best for you. |
| joint or all-metal hip joint. | | | | |